OpenVPN集成LDAP踩坑记

Updated on Dec 14, 2023 with 0 views and 0 comments

自建 VPN

需求：直接替换阿里云购买的 SSL VPN，硬刚……

openvpn 版本：2.4.9-1.el7
ease-rsa 版本：3.0.7-1.el7
openvpn-auth-ldap 版本：2.0.3-17.el7

搭建过程

安装 openvpn 和 easy-rsa
yum install -y openvpn easy-rsa
创建 easy-rsa key 的存放位置
mkdir -p /etc/openvpn/easy-rsa/keys
复制相关文件至 Openvpn 目录

cp /usr/share/doc/openvpn-2.4.9/sample/sample-config-files/server.conf /etc/openvpn
cp -rf /usr/share/easy-rsa/3.0/* /etc/openvpn/easy-rsa/
cp /etc/openvpn/easy-rsa/openssl-easyrsa.cnf /etc/openvpn/easy-rsa/openssl.cnf

生成 tls-auth 文件
openvpn --genkey --secret /etc/openvpn/ta.key
创建 CA，并设置密码：

[root@cjz openvpn]# cd /etc/openvpn/easy-rsa/
[root@cjz easy-rsa]# ./easyrsa init-pki

init-pki complete; you may now create a CA or requests.
Your newly created PKI dir is: /etc/openvpn/easy-rsa/pki


[root@cjz easy-rsa]# ./easyrsa build-ca
Using SSL: openssl OpenSSL 1.0.2k-fips  26 Jan 2017

Enter New CA Key Passphrase:     #在此要输入ca的密码：（ca.com），需要输入两次。
Re-Enter New CA Key Passphrase: 
Generating RSA private key, 2048 bit long modulus
........+++
..+++
e is 65537 (0x10001)
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Common Name (eg: your user, host, or server name) [Easy-RSA CA]:limikeji  #此处要输入组织：（Open××× CERTIFICATE AUTHORITY）

CA creation complete and you may now import and sign cert requests.
Your new CA certificate file for publishing is at:
/etc/openvpn/easy-rsa/pki/ca.crt

创建服务端证书，生成请求，使用 gen-req 来生成 req

[root@cjz easy-rsa]# ./easyrsa gen-req cjzshilong
Using SSL: openssl OpenSSL 1.0.2k-fips  26 Jan 2017
Generating a 2048 bit RSA private key
............+++
..........................................................+++
writing new private key to '/etc/openvpn/easy-rsa/pki/easy-rsa-1945.QkcdZs/tmp.plZnLa'
Enter PEM pass phrase:
Verifying - Enter PEM pass phrase:
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Common Name (eg: your user, host, or server name) [cjzshilong]:

Keypair and certificate request completed. Your files are:
req: /etc/openvpn/easy-rsa/pki/reqs/cjzshilong.req
key: /etc/openvpn/easy-rsa/pki/private/cjzshilong.key

签发证书，签约服务端证书

[root@cjz easy-rsa]# ./easyrsa sign-req server cjzshilong
Using SSL: openssl OpenSSL 1.0.2k-fips  26 Jan 2017


You are about to sign the following certificate.
Please check over the details shown below for accuracy. Note that this request
has not been cryptographically verified. Please be sure it came from a trusted
source or that you have verified the request checksum with the sender.

Request subject, to be signed as a server certificate for 825 days:

subject=
    commonName                = cjzshilong


Type the word 'yes' to continue, or any other input to abort.
  Confirm request details: yes
Using configuration from /etc/openvpn/easy-rsa/pki/easy-rsa-1972.yu5li8/tmp.z0dO8n
Enter pass phrase for /etc/openvpn/easy-rsa/pki/private/ca.key:  
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'cjzshilong'
Certificate is to be certified until Aug 23 02:29:57 2022 GMT (825 days)

Write out database with 1 new entries
Data Base Updated

Certificate created at: /etc/openvpn/easy-rsa/pki/issued/cjzshilong.crt

生成 Windows 客户端 test 用户

[root@cjz easy-rsa]# ./easyrsa build-client-full test
Using SSL: openssl OpenSSL 1.0.2k-fips  26 Jan 2017
Generating a 2048 bit RSA private key
................................................................+++
.........+++
writing new private key to '/etc/openvpn/easy-rsa/pki/easy-rsa-2119.2QIQRw/tmp.k6ehaI'
Enter PEM pass phrase:
Verifying - Enter PEM pass phrase:
-----
Using configuration from /etc/openvpn/easy-rsa/pki/easy-rsa-2119.2QIQRw/tmp.nFtxKF
Enter pass phrase for /etc/openvpn/easy-rsa/pki/private/ca.key:
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'test'
Certificate is to be certified until Aug 23 02:33:16 2022 GMT (825 days)

Write out database with 1 new entries
Data Base Updated

注：生成客户端用户的时候会提示设置密码，可以直接回车密码为空，也可以输入密码，待客户端连接时需要输入密码。

查看客户端证书存放路径：

ls -l /etc/openvpn/easy-rsa/pki/issued/test.crt 
ls -l /etc/openvpn/easy-rsa/pki/private/test.key

配置 sysctl.com 文件
vim /etc/sysctl.conf
在末尾加入:net.ipv4.ip_forward=1
最后执行：
[root@cjz easy-rsa]# sysctl -p
配置 /etc/openvpn/server.conf

port 1194   #端口：1194
proto udp  #协议使用：UDP
dev tun
ca /etc/openvpn/easy-rsa/pki/ca.crt  #此处配置的是绝对路径
cert /etc/openvpn/easy-rsa/pki/issued/cjzshilong.crt
key /etc/openvpn/easy-rsa/pki/private/cjzshilong.key  # This file should be kept secret
dh /etc/openvpn/easy-rsa/pki/dh.pem
server 10.8.0.0 255.255.255.0   #内网服务器虚拟地址
ifconfig-pool-persist ipp.txt
push "route 172.16.0.0 255.255.0.0"
push "redirect-gateway def1 bypass-dhcp"    #使客户端所有网络通信通过vpn
push "dhcp-option DNS 223.5.5.5"   #配置DNS
push "dhcp-option DNS 114.114.114.114"
keepalive 10 120
tls-auth /etc/openvpn/ta.key 0 # This file is secret
cipher AES-256-CBC
comp-lzo
max-clients 100  # 最大客户端连接数量
user openvpn
group openvpn
persist-key
persist-tun
status openvpn-status.log  # 状态日志
log-append  /var/log/openvpn/openvpn.log  # 开启OpenVpn日志
verb 3
mute 20
explicit-exit-notify 1

启动 openvpn
systemctl start openvpn@server
查看状态：

[root@cjz ~]# ps -aux | grep openvpn
openvpn  11941  0.0  0.1  77636  4940 ?        Ss   May19   0:01 /usr/sbin/openvpn --cd /etc/openvpn/ --config server.conf
root     12992  0.0  0.0 112708   988 pts/2    S+   10:44   0:00 grep --color=auto openvpn

查看安装 openvpn 后的网卡状态：

[root@cjz ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:16:3e:10:39:70 brd ff:ff:ff:ff:ff:ff
    inet 172.16.16.55/24 brd 172.16.16.255 scope global dynamic eth0
       valid_lft 315295137sec preferred_lft 315295137sec
8: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 100
    link/none 
    inet 10.8.0.1 peer 10.8.0.2/32 scope global tun0
       valid_lft forever preferred_lft forever

客户端安装连接

windows 64 位的 openvpn 版本为：2.4.9 可以从官网上下载
下载链接：https://openvpn.net/community-downloads/

客户端需要的证书文件：
tese.crt test.key ca.crt ta.key
创建一个存放客户端证书的文件夹，然后将客户端的证书下载到本地电脑

[root@cjz ~]# cd /etc/openvpn/client/
[root@cjz client]# ll
total 20
-rw------- 1 root root 1159 May 19 18:22 ca.crt
-rw------- 1 root root  636 May 19 18:22 ta.key
-rw------- 1 root root 4418 May 19 18:22 test.crt
-rw------- 1 root root 1834 May 19 18:22 test.key

复制完成后，将客户端正在下载到本地电脑，在此不详细描述。
然后需要在本地电脑上创建客户端配置文件：config.ovpn ,具体配置信息如下：

client
dev tun
proto udp
resolv-retry infinite
nobind
remote 182.x.x.141 1194 #此处要更换成出口的公网IP地址
ns-cert-type server
comp-lzo
ca ca.crt
cert test01.crt
key test01.key
tls-auth ta.key 1
keepalive 10 120
persist-key
persist-tun
verb 5
redirect-gateway
route-method exe
route-delay 2
status test01-status.log
log-append test01.log

安装 Openvpn 2.4.9 x86_64 后，需要找到客户端安装目录下的 config 文件夹，清空 config 文件夹，然后将客户端证书和客户端配置文件复制到 config 文件夹下

直接对标阿里云 SSL VPN

其他

如果生成证书时输错密码了（如 test 用户），报出如下错误：

需要删除以为文件后，可继续创建

[root@cjz easy-rsa]# rm -f  /etc/openvpn/easy-rsa/pki/reqs/test01.req 
[root@cjz easy-rsa]# rm -f  /etc/openvpn/easy-rsa/pki/private/test01.key

撤销证书（test 为例）
撤销命令：revoke
./easyrsa revoke test
生成 CRL 文件（撤销证书的列表）
./easyrsa gen-crl
重启 Openvpn 服务生效

systemctl stop openvpn@server
systemctl start openvpn@server

防火墙开放 1194 端口，阿里云需要在 ESC 的安全组中添加策略，开放 1194 端口。要不然映射后也访问不了(同时如果为了访问其他网段的机器，需要在专有网络中添加路由)
如果连接 OpenVPN 没问题的话，但是访问 Internet 却不行，这是需要开启虚拟网段进行 nat 转发

#开启NAT转发
iptables -I FORWARD -j ACCEPT   ###开启所有转发 
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

OpenVPN 集成 LDAP

OpenVPN 服务端集成的 OpenLDAP 认证，这样能够使客户端用户在连接 VPN 时直接使用统一的 OpenLDAP 账号

安装 openvpn-auth-ldap

yum install openvpn-auth-ldap -y

主要会安装 /usr/lib64/openvpn/plugin/lib/openvpn-auth-ldap.so 文件，和生成 /etc/openvpn/auth/ldap.conf 文件。

配置 vim /etc/openvpn/auth/ldap.conf

<LDAP>
	URL		ldap://172.16.16.4:389
	BindDN		cn=manager,dc=limikeji,dc=com
	Password	limikeji.com
	Timeout		15
	TLSEnable	no
	FollowReferrals no
</LDAP>

<Authorization>
	BaseDN		"dc=limikeji,dc=com"
	SearchFilter   "uid=%u"
	RequireGroup	false
	<Group>
		BaseDN		"ou=group,dc=limikeji,dc=com"
		SearchFilter	"cn=chanpinyanfabu"
		MemberAttribute	uniqueMember
	</Group>
</Authorization>

注意上面的 ldap.conf 中如果设置 RequireGroup true 以及 Group 的配置实际我们期望是必须是 LDAP 中的名称为 VPN 的组下的用户才可以登录 VPN。但根据这个 ISSUE，当前 2.0.3 的 openvpn-auth-ldap 不支持。因此如果只想限制 LDAP 中某些用户可以使用 VPN 的话，只能设置 RequireGroup fals，然后可以在 SearchFilter 中做一些文章，比如(&(uid=%u)(ou=vpn))即只有用户的 ou 字段为(vpn)的才可以。

配置 /etc/openvpn/server.conf，添加如下：

...
plugin /usr/lib64/openvpn/plugin/lib/openvpn-auth-ldap.so "/etc/openvpn/auth/ldap.conf"
client-cert-not-required
...

使用了上面安装的 openvpn-auth-ldap 认证插件
client-cert-not-requir 不再需要客户端证书，将改为使用 OpenLDAP 中的用户认证

客户端配置：

client
dev tun
proto udp
resolv-retry infinite
nobind
remote 182.x.x.141 1194 #此处要更换成出口的公网IP地址
ns-cert-type server
comp-lzo
ca ca.crt
;cert test01.crt
;key test01.key
tls-auth ta.key 1
keepalive 10 120
persist-key
persist-tun
verb 5
auth-user-pass
redirect-gateway
route-method exe
route-delay 2
status OpenVpnClient-status.log
log-append test01.log